Age-related changes in hearing and cognition pose considerable challenges to older adults in real world settings. Traditional methods of assessing audiometric functioning fail to consider the attentional processing requirements inherent in everyday listening situations. Concurrently, cognitive aging research has often neglected to adequately measure and account for hearing abilities. Hearing impairment, common among older populations, necessitates the expenditure of differentially greater attentional resources for signal extraction thereby compromising performance on concurrent cognitive tasks. New in-vehicle technologies utilizing auditory guidance instructions to assist drivers with navigating through complex and unfamiliar environments have the potential to decrease the attentional demands of difficult ddving situations and thus increase the safety and mobility of older ddvers. However, failure to address the interacting affects of declining hearing abilities and attentional processing capabilities of older adults threatens the effective implementation of these new technologies. Standard methods of assessing hearing impairment (i.e., clinical audiometry) neglect the working memory demands involved in everyday auditory processing. At the same time, conventional assessments of cognitive processing often use auditory tasks but frequently do not assess hearing ability adequately. The major goal of the proposed research is to develop and validate a functional hearing assessment methodology with young, young-old and old adults to examine the impact of hearing ability on speech processing and attentional workload during multi-task performance similar to that present in many everyday situations. To achieve this goal, three experiments of multi-task performance are proposed. A speech-processing task will be combined with a simulated driving task. Experiment 1 will facilitate the establishment of a method of assessing functional hearing ability (FHA) and Experiment 2 will examine the impact of realistic environmental noise on FHA. Auditory stimuli will first be presented within a range of presentation levels including standard (60dB), attenuated and amplified presentation levels. By equating functional hearing level between the age groups, a comparison of the attentional requirements of the speech-processing task independent of hearing ability can be achieved. Results of the investigation will be utilized to develop a predictive model of the attentional requirements of auditory processing in real world multi-task situations such as driving. Experiment 3 will incorporate the results of the FHA methodology established in Experiments 1 and 2 in a realistic driving task involving utilizing auditory navigational guidance instructions to complete a wayfinding task.